Allyl alcohol, which is made commercially by isomerizing propylene oxide, is widely used to make allyl ether and allyl ester derivatives for pharmaceuticals, fragrances, and chemical intermediates. Allyl alcohol advantageously features both hydroxyl and olefin functional groups; however, because it is flammable and highly toxic, allyl alcohol must be handled carefully. For many applications, propoxylated allyl alcohols, i.e., reaction products of allyl alcohol and an equivalent or two of propylene oxide, are favorable replacements for allyl alcohol because they have the same functional groups (and similar reactivity), but are less volatile and less toxic.
Allyl alcohol copolymerizes with vinyl aromatic monomers such as styrene (See, for example, U.S. Pat. Nos. 2,894,938 and 2,940,946). Because of the large reactivity difference between the monomers, the process is run with a large excess of allyl alcohol; unreacted allyl alcohol is recovered by distillation and is then recycled to the polymerization reactor. The resulting styrene/allyl alcohol copolymers are used in a variety of products, including polyesters, fatty ester emulsions, and uralkyds. The insolubility of styrene/allyl alcohol copolymers in polyether polyols limits their usefulness in polyurethane foams.
Hult and Johansson (J. Polym. Sci., Part A, Polym. Chem. Ed. 29 (1991) 9) polymerized styrene in the presence of up to 12 mole percent of ethylene glycol monoallyl ether or propylene glycol monoallyl ether, and concluded that allyl ethers do not copolymerize with styrene, but inhibit styrene polymerization.
Copolymers of vinyl aromatic monomers and higher molecular weight polyether polyols containing unsaturation are known. For example, U.S. Pat. No. 3,823,201 (Pizzini et al.) teaches graft copolymer dispersions made by reacting vinyl monomers with polyether polyols having functionalities of 2 to 6, preferred equivalent weights of 250 to 5000, and unsaturations of 0.10 to 0.70 meq/g. U.S. Pat. No. 4,264,755 (Cross) teaches hydroxy-functional vinyl copolymers produced by copolymerizing styrene with a mono- or diallyl ether of a saturated aliphatic polyol having a hydroxyl functionality of 3-4. The resulting copolymers have hydroxyl numbers from 45 to 100, and number average molecular weights from 7,000 to 20,000.
U.S. Pat. No. 4,722,978 (Yu) teaches allyl-terminated polyether macromonomers ("macromers"). Cationic polymerization of an epoxide or glycidyl ether in the presence of an allylic alcohol starter gives a macromer that has from 2 to 500 oxyalkylene units. The macromer copolymerizes with vinyl monomers, including styrene. New copolymers derived from allyl monomers and vinyl aromatic monomers are needed. Preferably, the copolymers would be soluble in polyether polyols, and could be made from monomers that are volatile enough to recover from a polymerization mixture by distillation. Copolymers useful in a variety of alkyd resin, polyurethane, and melamine-based products, especially coatings, would be desirable.